Hydrogenation process for alcohols



United States Patent O HYDROGENATION PROCESS FOR ALCOHOLS Lawrence Rogovin, Cincinnati, Ohio, and Andrew 0.

Wikman, Baton Rouge, La., assignors of one-half each to The Procter & Gamble Company, Cincinnati, Ohio,

a corporation of Ohio, and Ethyl Corporation, Richmond, Va., a corporation of Virginia No Drawing. Filed June 29, 1966, Ser. No. 561,348

Int. Cl. C07c 29/24 US. Cl. 260643 3 Claims ABSTRACT OF THE DISCLOSURE A hydrogenation-purification process for alcohols having about 6 to about 24 carbon atoms, particularly those alcohols having about 12 to about 16 carbon atoms, produced by the Ziegler process for alcohol synthesis comprising two distinct steps of hydrogenation performed in either possible order wherein one of the hydrogenation steps is carried out using a copper chromite catalyst, while the other hydrogenation step uses a nickel catalyst. The hydrogenation process results in detergent derivatives, including alkali earth metal salts, ammonium salts and triethanolamine salts of alkyl sulfate, alkyl ether sulfate and alkyl glycerol ether sulfonate derivatives and formulations of the treated alcohols which exhibit a low and pleasant odor level substantially like that of derivatives and formulations produced from naturally derived (Z -C alcohols, for example coconut alcohols.

This invention relates to the utilization of synthetic alcohols, as opposed to alcohols derived from natural sources, having about 6 to about 24 carbon atoms and has for its general object the provision of a hydrogenation process whereby said synthetic alcohols exhibit a low and pleasant odor level when converted into useful derivatives. More particularly, the invention provides a hydrogenation process whereby the salts of alkyl sulfates, alkyl ether sulfates and other detergent derivatives prepared from synthetic alcohols having about 6 to about 24 carbon atoms are rendered substantially as odoriferously suitable for use in detergent formulations as those prepared from naturally derived alcohols. Specifically, the invention provides a hydrogenation process whereby the alkali earth metal salts, the ammonium salts andthe triethanolamine salts of alkyl sulfate, alkyl ether sulfate and alkyl glycerol ether sulfonate derivatives of middlecut alcohols, alcohols having about 12 to about 16 carbon atoms, produced by the Ziegler process for alcohol synthesis are caused to exhibit a low and pleasant odor level in perfumed or nonperfumed detergent formulations, which odor level is substantially like that of the detergent derivatives produced from naturally derived C12C16 alcohols, for example coconut alcohols.

The Ziegler process for the production of synthetic alcohols can be generally described as a reaction wherein aluminum trialkyls are formed from olefines, oxidized and subsequently hydrolyzed to form alcohols with carbon chain lengths corresponding to the alkyl groups of the aluminum trialkyls. A process for the production of the synthetic alcohols of interest in the present process is disclosed in US. 2,892,858 issued to Karl Ziegler on June 30, 1959, while a process for preparing the trialkyl and 3,505,414 Patented Apr. 7, 1970 other suitable aluminum hydrocarbon starting materials from olefincs is disclosed in US. 2,835,689, issued to Karl Ziegler on May 20, 1958. Synthetic alcohols produced by other processes, for example the oxo process, will also benefit from the hydrogenation process of the present invention.

In order to convert the C C alcohols, particularly the synthetic middle-cut alcohols, produced by the Ziegler process to alkyl sulfates for use in detergent formulation the alcohols are sulfated. Sulfation is generally accomplished 'by contacting the alcohols with a sulfating agent, for example sulfuric acid, oleum, chlorosulfonic acid or sulfur trioxide, according to procedures so widely understood and practiced in the industry as to require no further discussion herein. The alkyl ether sulfates can be produced by reacting the alcohols with ethylene oxide prior to sulfation, e.g. one to .thirty moles of ethylene oxide. The acid forms of the detergent derivatives are converted into desired salts by neutralization with appropriate reagents for use in detergent formulations.

Unfortunately, although the alcohols synthesized by the Ziegler process provide a virtually limitless source of C C alcohols as opposed to the limited supply afforded by natural crops such as coconut meats or copra, applicant and others have realized that the salts of alkyl sulfates, alkyl ether sulfates and other detergent derivatives prepared from synthetic alcohols produced by the Ziegler process, hereinafter discussed by reference to the alkyl and alkyl ether sulfates, exhibit a high and objectionable odor level. The type of odor, which odor has been variously described as having a refinery smell or an olefine smell, and its relative high level or strength has made the use of the salts of alkyl sulfates, alkyl ether sulfates derived from Ziegler alcohols objectionable in many detergent formulations. In the field of perfumed detergent formulations, which formulations appear to be preferred by the housewife in the present state of the detergency art, the odor of alkyl or alkyl ether sulfate salts derived from synthetic alcohols is definitely a problem. The problem stems from the fact that many otherwise desirable perfuming ingredients will not mask the unpleasantness of the synthetic alkyl or alkyl ether sulfate salts and so cannot be freely selected for use. In other instances the perfuming agents selected are sufliciently powerful to mask the unpleasant odor, but only when these relatively high priced and in many cases hard to secure in commercial quantity agents are used in excessive and wasteful amounts. A problem also exists in the use of the synthetic alkyl or alkyl ether sulfate salts in nonperfumed formulations where any unpleasant odor is not masked. The C C and C -C alcohols or sulfated derivatives thereof are also used in formulations and compositions used by humans. The odor problem results in a limitation on the use of synthetic alcohols which does not exist in the use of naturally derived alcohols.

In the detergency use of alkyl or alkyl ether sulfate salts derived from the middle-cut alcohols produced by the Ziegler synthesis, the advantage of the process of this invention is clear-cut in permitting a wider choice and level of perfumir-g agent, even to subtle perfuming agents, in detergency formulations. In the case of the C C synthetic alcohols and C -C synthetic alcohols, whose alkyl or alkyl ether sulfates or their salts are normally not employed in detergency formulations, the advantage is still inherent in the solvent and plasticity uses to which these materials are put, in that high and unpleasant odor levels are also objectionable in these uses.

Applicant has unexpectedly discovered that a two-step hydrogenation process practiced on the above-described synthetic alcohols will substantially obviate or render the odor problem negligible in connection with their use as alcohols or derivatives of alcohols. The process of this invention provides a means of reducing the odor level of synthetic alcohols and their derivatives so that they are rendered interchangeable with natural alcohols in uses where odor is a factor.

It is, therefore, an object of thiss invention to provide a novel two-step hydrogenation process to be used in the treatment of synthetic alcohols to render said synthetic alcohols and their derivatives interchangeable with natural alcohols in use for purposes of odor characteristics.

It is a further object of this invention to provide a two-step hydrogenation process which obviates the high and objectionable odor level inherent in alkyl or alkyl ether sulfate salts derived from alcohols prepared by the Ziegler olefine build-up process for the production of synthetic alcohols.

It is a still further object of this invention to provide a novel two-step hydrogenation process for (3 43 alcohols produced by the Ziegler aluminum hydrocarbon synthesis which renders the alkyl or alkyl ether sulfate salts subsequently derived from said C -C alcohols especially suitable for use in detergent formulations.

These and other objects, which will become apparent from the discussion and examples hereinbelow, are achieved by practice of the present invention which is directed to a process for a two-stage hydrogenation treatment of C C alcohols produced by the Ziegler aluminum hydrocarbon alcohol synthesis. In general the process comprises the application of two steps of hydrogenation to the synthetic alcohols which hydrogenation steps can be carried out in either batchwise or continuous manner using conventional equipment. The two necessary stages of hydrogenation can be conducted in a continuous manner with either a catalyst slurry or a fixed bed of catalyst according to conventional procedures. The essential feature of the process is that one of the hydrogenation steps is carried out using a copper chromite catalyst, while the other hydrogenation step uses a nickel catalyst. The hydrogenation steps using two differential catalysts can be carried out in either possible sequence so that the first hydrogenation step can comprise either a nickel or a copper chromite catalyzed hydrogenation.

As the term hydrogenation is generally used, a hydrogenation step is used to effect some gross physical or chemical change in the starting material. For example, olefines can be hydrogenated to form parafiins having a higher melting point than the starting olefines, while aldehydes and ketones can be hydrogenated to form alcohols. These hydrogenations consume a relatively large amount of hydrogen.

In contrast, the two hydrogenation steps of the present invention consume a relatively small amount of hydrogen and do not grossly change the physical or chemical properties of the starting alcohols. It is usually surprising when a relatively unrelated processing step elfects a noticeable change in the physical properties of the product of a subsequent processing step. While applicant might have expected some change resulting from a single hydrogenation to cleave or saturate by-products in the synthetic alcohols, the necessity of performing two stepwise hydrogenations on synthetic alcohols using separate catalysts to achieve a low and pleasant odor level in their subsequently derived alkyl sulfate salts was entirely unexpected and unobvious. Indeed applicant did apply a nickel catalyzed hydrogenation to the synthetic alcohols and achieved only a reduction in iodine value, which reduction had a known and beneficial effect in improving the keeping and color properties of the alcohols and their derivatives, but was not effective in rendering their odor acceptable. It was only when applicant applied both a nickel and a copper chromite hydrogenation to the alcohols that their odor level and the odor level of their derivatives was rendered substantially interchangeable with that of naturally derived alcohol products.

The copper chromite catalyzed hydrogenation of the present invention can be carried out in batch-wise or continuous fashion in conventional hydrogenation equipment at a temperature of about 300 F. to about 500 F. with a hydrogen gas pressure of about 15 p.s.i.g. to about 1000 p.s.i.g. for periods of about 5 minutes to about 60 minutes. An amount of copper chromite hydrogenation catalyst equal to about 0.1% to about 3.0% by weight of the alcohols is employed in the hydrogenation. The nickel catalyzed hydrogenation can be carried out at a temperature of about 400 F. to about 550 F. with a hydrogen gas pressure of about p.s.i.g. to about 1500 p.s.i.g. for periods of about 5 minutes to about 60 minutes. An amount of nickel hydrogenation catalyst equal to about 0.1% to about 3.0% by weight of the alcohols is employed in the hydrogenation. Those skilled in the art will understand that the time, temperature, pressure and cata lyst level of hydrogenation processes can be varied considerably, according to such factors as equipment volume limitations and economic factors in the amount of catalyst used, while obtaining substantially the same result from the hydrogenation.

Applicant prefers however, to carry out the two hydrogenation steps in either sequence as stated above, with a copper chromite catalyzed hydrogenation carried out at about 400 -F. with a hydrogen gas pressure of about 500 p.s.i.g. for a period of about 20 minutes using about 0.1% of copper chromite hydrogenation catalyst based on the weight of the alcohols. The preferred nickel catalyzed hydrogenation is carried out at a temperature of about 400 F. with hydrogen gas pressure of about 500 psig. for a period of about 20 minutes using about 0.1% of nickel hydrogenation catalyst based on the weight of the alcohols Both the copper chromite and the nickel hydrogenation catalysts can be promoted with added materials according to conventional practices in the hydrogenation art.

While applicant prefers the above stated conditions for the two hydrogenation steps essential to the practice of this invention, it will be understood by those skilled in the art, as stated above, that the conditions of a given hydrogenation step can be quite widely varied while maintaining a desired result. In particular, increases in either or both the temperature and the pressure in hydrogenation process will generally make possible a reduction in the period of time required for the hydrogenation to take place..Similarly, an increase in the amount of catalyst will. generally shorten the time required to achieve a given hydrogenation result. In the same sense, if a longer periodof time can be allowed for hydrogen either or both the temperature and the pressure can generally be reduced.

As stated above, the essential requirement to the practice of the present invention is the carrying out of two hydrogenations, one'catalyzed by nickel and the other catalyzed by copper chromite, on the synthetic alcohols prior to their conversion into alkyl or alkyl ether sulfate salts. The two hydrogenations can be carried out in either sequence to achieve the benefit of this invention, although applicant prefers to carry out the copper chromite catalyzed hydrogenation first, because it generally is accompanied by an undesirable increase in ester value. The subsequent nickel hydrogenation reduces and controls the ester value in addition to reducing the iodine value of the alcohols to achieve the beneficial effects in color and keeping quality previously discussed.

The hydrogenation steps have been described by giving their time, temperature and pressure conditions since they can be carried out in conventional hydrogenation apparatus of either a batch or a continuous nature. Also the necessary catalytic material in the two hydrogenations can be present either as a powdered catalyst or as supported on a fixed bed, or in addition it can be present in any other physical form conventional in the catalytic art as applied to hydrogenation processes.

In addition to the hydrogenation steps described above, it will also be found beneficial in the practice of the present invention to distill or redistill the alcohols subsequent to or between the hydrogenation steps. Such a distillation or redistillation results in a slight additional improvement in odor. In particular, when the two-step hydrogenation is practiced on crude Ziegler alcohols containing C C alcohols, a very suitable middle-cut C -C alcohol fraction for use in the preparation of alkyl and alkyl ether sulfate salts can be obtained by first fractioning the two-step hydrogenated alcohols to remove C C alcohols and then distilling off the middle-cut C C alcohols. Also, the first step of the two-step hydrogenation can be carried out on C -C alcohols whereupon the alcohols are fractionated to obtain the middlecut C 41 alcohols which are then accorded the second hydrogenation step. In another variation of the process, middle-cut C -C alcohols obtained by fractionation can be accorded both hydrogenation steps and then redistilled. Other sequences of distillation and hydrogenation employing the two hydrogenation steps of the present process will also be found beneficial, as will process sequences which employother conventional purification steps, for example treatments using a molecular sieve or activated carbon.

The following examples will illustrated in detail the manner in which the invention can be practiced. It will be understood, however, that the invention is not confined to the specific limitations set forth in the individual examples but rather to the scope of the appended claims.

In the examples, the initial C C Ziegler alcohol has the following approximate distribution (ignoring minute 100 parts by weight of C C alcohol produced by the Ziegler process for the production-of synthetic alcohols are placed in an autoclave equipped with a propeller for mechanical agitation together with 0.1 part by weight of powdered copper chromite hydrogenation catalyst. The autoclave is then sealed, and the internal pressure of the autoclave is raised to 500 p.s.i.g. by introducding hydrogen gas under pressure. The internal pressure in the auto clave of 500 p.s.i.g. is maintained during the copper chromite hydrogenation by the introduction of additional hydrogen as required.

The contents of the autoclave are then heated to a temperature of 400 F. by means of external heaters, and the stated conditions of temperature conditions are maintained for 20 minutes. At the end of the twenty minute hydrogenation period, the autoclave is cooled and vented prior to removing the copper chromite catalyst hydrogenated alcohols, and the copper chromite catalyst is removed from the alcohols by centifugation and filtration.

Next parts by weight of the catalyst-free, copper chromite catalyst-hydrogenated C C alcohols are placed in an autoclave equipped with a propeller for mechanical agitation together with 0.1 part by weight thereof of powdered Raney nickel hydrogenation catalyst. The autoclave is then sealed, and the internal pressure of the autoclave is raised to 500 p.s.i.g. by introducing hydrogen gas under pressure. The internal pressure of 500 p.s.i.g. in the autoclave is maintained during the nickelcatalyzed hydrogenation by the introduction of additional hydrogen as required. The stated temperature and pressure is maintained for 20 minutes, whereupon the autoclave was cooled and vented. The nickel and copper chromite hydrogenated contents of the autoclave is then removed, and the nickel hydrogenation catalyst is separated therefrom by centrifugation and filtration.

Two-step hydrogenated alcohols are then fractionated by high vacuum distillation to remove substantially all of the C -C alcohols, which alcohols are suitable for use in low odor plastics formulations. The middle-cut C C alcohols are subsequently obtained by fractional distillation.

The middle-cut C -C alcohols are then sulfated by contacting them with 102% of the theoretical amount of chlorosulfonic acid at F. for 10 minutes to produce their alkyl sulfate derivatives. The alkyl sulfate derivatives are neutralized with sodium hydroxide at a temperature of 110 F. to form their sodium alkyl sulfate salts. The sodium alkyl sulfate salts of the two-step hydrogenated middle-cut alcohols are found to have a low and pleasant odor level substantially like that of the sulfuric ester salts of comparable alcohols obtained from coconut meats. The two-step hydrogenated synthetic alcohol derivatives are found to be quite suitable for use in perfumed and nonperfumed detergent formulations.

The odor results of the two-step hydrogenation process of Example I above together with the results of other twostep hydrogenations are given in the table below. The odor results of a one-step copper chromite catalyzed and a one-step nickel catalyzed hydrogenation of synthetic alcohols are also given in the table below for comparison. The alkyl ether sulfate salts contained an average of 3 moles of ethylene oxide.

TABLE IContinued Second-Step Hydrogenation Amount of catalyst based on alcohol, weight percent Hydrogenation catalyst Pressure, Temp., F.

Time, minutes Odor level as compared The results of all of Examples I-V in Table I above illustrate that the two-step hydrogenation process of the present invention can be applied to synthetic alcohols with the result that equal odor levels in detergent derivatives as compared with comparable natural alcohol derivatives are obtained. The results of Runs 1, 2 and 3 illustrate that the detergent derivatives prepared from synthetic alcohols which are not accorded the two-step hydrogenation, i.e., prepared from synthetic alcohols accorded either a single hydrogenation or no hydrogenation treatment, have a higher odor level than the detergent derivatives resulting from the two-step processes of Examples I-V. All of the detergent derivatives prepared in Examples I-V were suitable for interchangeable use with comparable detergent derivatives derived from natural alcohols.

Although the present invention has been described and illustrated with reference to specific examples, it will be understood that modifications and variations can be made without departing from the spirit and scope of the invention set forth in the following claims.

What is claimed is:

1. A two-step hydrogenation-purification of C -C alcohols prepared by the oxidation and subsequent hydrolysis of aluminum alkyls which comprises the two distinct steps in sequence of:

(1) a first step of a nickel catalyzed hydrogenation conducted at a pressure of about 100 p.s.ilg. to about 1500 p.s.i.g. and a temperature of about 400 F. to about 550 F. for about 5 minutes to about 60 minutes using about 0.1% to about 3.0% of nickel hydrogenation catalyst consisting essentially of nickel based on the weight of alcohols hydrogenated, and then (2) a copper chromite catalyzed hydrogenation conducted at a pressure of about 15 p.s.i.g. to about 1000 p.s.i.g. and a temperature of about 300 F. to about 500 F. for about 5 minutes to about 60 minutes using about 0.1% to about 3.0% of copperv chromite hydrogenation catalyst consisting essentially of copper chromite based on the Weight of alcohols hydrogenated.

2. The improvement of claim 1 wherein the synthetic alcohols treated have about 12 to about 16 carbon atoms.

3. The improvement of claim 1 wherein, in steps (1) and (2), the pressures are each about 500 p.s.i.g., the temperatures are each about 400 F., the times are each about 20 minutes and the catalyst amounts are each about References Cited UNITED STATES PATENTS 1,724,761 8/ 1929 Holden. 2,137,407 11/ 1938 Lazier; 2,416,901 3/1947 Carmody 252470 2,671,119 '3/ 1954 Mertzweiller. 2,900,423 8/1959 Smith 25247O 3,1 18,954 1/1964 Robbins et a1. 3,208,866 1 l/ 1966 Cooper. 3,373,211 3/1968 Watts et a1.

' FOREIGN PATENTS 929,325 a 6/ 1963 Great Britain.

LEON ZITVER, Primary Examiner I. E. EVANS, Assistant Examiner US, Cl. XLR. 252-161; 2604S8 

